M20J Main Gear Tire and Tube Recommendations

[A64Pilot]

20 hours ago, Martin S. said:

Evening gents,

picking up this topic as I plan to replace tubes + tires. I want to replace my main tire tubes with tubes that have the same stem type. Can somebody tell me what kind of stems (straight or 70 or 90 deg) I have, from the picture?

 

Many thanks + greets from Germany,

 

Martin 

To me they appear to be straight, but I believe the nose wheel requires an angled stem, I just replaced my mains s few months ago and should remember but I don’t.

Edited August 7, 2023 by A64Pilot

[Martin S.]

Ok - that's what I also thought. They look as if there were the straight stems. Thanks everybody.

Greets,

 

Martin

[AndreiC]

Two new questions on the same topic. 

1) One of my mains has a flat spot, but no cords showing. Does it need replacing at annual (in a month) or can it still go another year?

2) Being a CB, does the tube have to be replaced every time the tire is changed? It appears to hold pressure very well. 
 

Thanks! 

[Bartman]

I had a flat spot for several years. 
 

I have no confidence that an old tube that lasted the life of the old tire would last the life of a new tire, so I would not put an old tube in a new tire. Michelin Airstop. 

[cliffy]

Tubes (IMO) need to be replaced with each new tire  

WHY you ask?

When you remove the tire and pull the tube out of it look and see what is still in the tire.

You will see black rubber "dust" in the tire

That comes from the tube rubbing minutely on the tire inside every time the wheel rotates.

Think about every landing when you touch down how much the assembly flexes. The tube rubs the inside there every time. Every bump. every brake application that cause the tire to flex the tube rubs the inside of the tire.

This thins out the wall thickness of the tube,

Also every tube begins to stretch due to the inflation in the tire. They will be larger when deflated than when they were new 

Combine this with the fact that they are thinner due to the rubbing inside the tire and you get a fold inside the tire when you reinflate  the assembly. This leads to more rubbing and a hole in the tube in short order. 

Not the least of which is the problem of the valve stem (the only part of the tube exposed to weather the entire life of the tube) going bad and cracking causing a leak there (all of my tire failures in 25 years on the Mooney have been at the valve stem).

If you do decide to reuse the tube make sure you bend the valve stem before installation to see if you have ANY indication of cracks in the valve stem. I'll bet you will.

Granted tubes are about as expansive as the tire BUT its part of the pleasure of owning an airplane.

There are limits to the CB club.

[EricJ]

5 hours ago, Andrei Caldararu said:

Two new questions on the same topic. 

1) One of my mains has a flat spot, but no cords showing. Does it need replacing at annual (in a month) or can it still go another year?

A tire can be run until there is cord showing.    I've had a flat spot for many years.   It's finally looking like it's getting down near the cord, so I'll replace it when it does.

5 hours ago, Andrei Caldararu said:

2) Being a CB, does the tube have to be replaced every time the tire is changed? It appears to hold pressure very well. 
 

Thanks! 

It is generally a good idea to replace the tube when the tire is changed, as tires can last a long time if taken care of.    It is not required, though.

[PT20J]

I don't notice any rubber dust in mine, but I use a liberal amount of talc on assembly. 

The tubes are within the tires and thus protected from UV and ozone, so the rubber doesn't deteriorate like it would if exposed.

The biggest issue with tubes seems to be that they stretch and it's very easy when reusing a tube to get a fold in the tube between the tube and the tire. On the other hand, I've talked to mechanics that do a LOT more tire changes than me and they tell me that  tubes with folds are common and they work just fine that way.

Personally, I would replace the tubes when replacing tires, but I'm not at all sure it's necessary if they are carefully inspected, not too old (as in reused through several tire changes) and installed carefully.

[N201MKTurbo]

I usually replace tubes on every other tire chang. I think the tubes fail from rot, usually around the valve stem, which is the only part exposed to the atmosphere, or from tube growth. The tubes expand over time from being constantly stressed from inflation which causes the rubber to cold flow. They get so big they won't fit into the tire without wrinkles and folds. The tubes fail at the wrinkles and folds.

[Shadrach]

11 minutes ago, EricJ said:

A tire can be run until there is cord showing.    I've had a flat spot for many years.   It's finally looking like it's getting down near the cord, so I'll replace it when it does.

It is generally a good idea to replace the tube when the tire is changed, as tires can last a long time if taken care of.    It is not required, though.

Absolutely true. 

On the other hand, even with good speed management, Mooneys have a propensity to skid during braking due to the lift created in ground effect. This is exacerbated when there is standing water on the runway.  The tread on our aircraft tires is meager but I notice a significant difference in wet braking performance between old and new tires.  I rarely use brakes above taxi speed but I got a wakeup call going into an unfamiliar 2600' strip near Buffalo New York on a very wet day.  Less than stellar approach on a cold and rainy December day with lots of standing water was an attention getter. Still had plenty of margin, but not because I was getting expected braking performance.  

[N201MKTurbo]

I always use talc. I don't think it does anything after the tube is inflated, it just lubricates the tube as it is being inflated so it can find its happy spot in the tire without wrinkles and folds. I usually see see the printing from the tube impressed in the talc on the inside of the tire when I take out the tube. This indicates that the tube doesn't move once inflated. 

Of course we will never know for sure, there is no way I know of to see what the tube does when the tire is rolling. 

[Shadrach]

16 minutes ago, PT20J said:

I don't notice any rubber dust in mine, but I use a liberal amount of talc on assembly. 

The tubes are within the tires and thus protected from UV and ozone, so the rubber doesn't deteriorate like it would if exposed.

The biggest issue with tubes seems to be that they stretch and it's very easy when reusing a tube to get a fold in the tube between the tube and the tire. On the other hand, I've talked to mechanics that do a LOT more tire changes than me and they tell me that  tubes with folds are common and they work just fine that way.

Personally, I would replace the tubes when replacing tires, but I'm not at all sure it's necessary if they are carefully inspected, not too old (as in reused through several tire changes) and installed carefully.

I installed a used tube (airstop) once in a pinch over a weekend.  After several months of service, my motivation to install the new tube faded to zero.  I have the brand new Airstop I was to replace it with in a sealed bag in my on board too kit. That was almost 5 years ago.

[Shadrach]

3 minutes ago, N201MKTurbo said:

I always use talc. I don't think it does anything after the tube is inflated, it just lubricates the tube as it is being inflated so it can find its happy spot in the tire without wrinkles and folds. I usually see see the printing from the tube impressed in the talc on the inside of the tire when I take out the tube. This indicates that the tube doesn't move once inflated. 

Of course we will never know for sure, there is no way I know of to see what the tube does when the tire is rolling. 

I don't think there is much if any movement between tire and tube unless operated at pressures below spec.

[EricJ]

The advice I've seen to minimize folds/wrinkles is to assemble the tire, inflate the tube to pressure, deflate it again, wiggle everything around a little, then inflate it to pressure for use.    If there's a wrinkle the inflation/deflation/inflation cycle usually flattens it out.

I always put the dot on the filler tube and monitor whether the tire slips.    I've not seen this be much of a problem on aircraft tires, but on race tires it was often an issue if one was concerned about balance (which usually we weren't).   It's not unusual for a race tire to slip on a wheel, but they're always tubeless.   If a tubed tire did it it'd likely be a bigger problem, so I try to keep an eye on mine.

[Marc_B]

1 hour ago, Shadrach said:

This is exacerbated when there is standing water on the runway.

^This.  From what I understand there is plenty of rubber left to wear past the time the tread is gone, but the wet/contaminated runway stopping distance greatly increases.  But the general rule of thumb I've been taught is replace if cords showing, or any one tread line gone.  Given the potential cost of an off runway excursion, seems poor tube/tire mgmt is penny wise, pound foolish at least for me personally.  The Mooney is a race car, I just wish my shop had the staff and funding to run like a pit crew!

[Fly Boomer]

On 8/22/2023 at 5:34 AM, Andrei Caldararu said:

Two new questions on the same topic. 

1) One of my mains has a flat spot, but no cords showing. Does it need replacing at annual (in a month) or can it still go another year?

2) Being a CB, does the tube have to be replaced every time the tire is changed? It appears to hold pressure very well. 
 

Thanks! 

Lots of great info on wear modes and such above.  The tire is probably fine but, when you do change the tire, I would suggest replacing the tube just because it can be a monumental screwup when it fails.

[Kelpro999]

Liberal application of talc is key to maintaining tube life. Every single deflection of tire results in movement between tire I.D. and tube O.D. Talc seems to be the best accepted lubricant I’ve seen. In motorcycle racing I was involved with for most my life, removing tubes without talc was obvious by the amount of abrasion wear on the tubes, sometimes 1/2 the thickness worn away then pinch flats or bleeding air. This may not be apples to apples but the idea is same. Plane wheels don’t see the same duty cycles but it’s still happening.

[Danb]

Embarrassingly I just flat spotted my tire the first time. It has a flat spot no cord showing trying to determine to have it changed or wait till I get home. Gotta always stay on your game or stupid stuff happens 

D

[EricJ]

6 minutes ago, Danb said:

Embarrassingly I just flat spotted my tire the first time. It has a flat spot no cord showing trying to determine to have it changed or wait till I get home. Gotta always stay on your game or stupid stuff happens 

D

If it's not shaking during takeoff or landing, I'd suggest leaving it on until cord is showing or nearly showing.   At least, you don't need to change it until then.    I've had a flat spot on one of my Goodyears for many years.   It doesn't shake or vibrate, you'd never know it was there without looking.    It's finally getting close to needing to be changed, but cord isn't showing quite yet... 

 

[N201MKTurbo]

I had a partner in my plane when I first bought it. He didn't fly it that much. I could tell how many times he flew it by the flat spots on the tires. If I changed tires every time they got a flat spot, we couldn’t afford to fly. I did consider amending the agreement to include a $100 surcharge for each flat spot.

[FLYFST]

The tubes I'm planning to use for the main gear in my 1990 J are 092-500-0 | G15/6.00-6 TUBE TR-20 / Straight Michelin AirStop.  Can anyone confirm the picture from my J shows a TR-20 Straight Stem as opposed to the TR-67 or TR-87 angled stem? 

Thanks - Hank

[EricJ]

19 minutes ago, FLYFST said:

The tubes I'm planning to use for the main gear in my 1990 J are 092-500-0 | G15/6.00-6 TUBE TR-20 / Straight Michelin AirStop.  Can anyone confirm the picture from my J shows a TR-20 Straight Stem as opposed to the TR-67 or TR-87 angled stem? 

Thanks - Hank

I just today took this pic of mine, since I just put a new tire and Michelin airstop tube on that gear and wanted to make a record to track any tire slippage.    This is the TR-20 as bought from AS.

[FLYFST]

1 minute ago, EricJ said:

I just today took this pic of mine, since I just put a new tire and tube on that gear and wanted to make a record to track any tire slippage.    This is the TR-20 as bought from AS.

Great, thanks, definitely same as mine.

[jetdriven]

On 1/18/2022 at 4:05 PM, 201er said:

Thing is, I don't think you need to touch the brakes to slowly develop a flat spot. They have a tendency to touchdown on the same spot every time, so it gets worn harder than everywhere else. I've noticed this on every set of tires I've had including the Goodyear III's. Whatever spot reaches cord first is the end of your tire, even if there's a bunch left everywhere else.

The Goodyear Flight Custom III are 2x the price of Air Hawks. From what I heard and my own experience, they last 2x the number of landings. From a maintenance perspective, that's half the work and should be slightly better value that way. However, they're already pulling the wheels at annuals so if you get it replaced then, it doesn't add anything. However, a flat spot from braking or repeated touchdown wear can end the tire's life early. For this reason, replacing the half price airhawks twice as often is my preferred way to go.

The tires are 125$ but the tubes are 200$. So changing them twice as often is false economy. 

[Will.iam]

Retract the flaps before applying the brakes will significantly lower your chances of locking up the brakes and flat spotting a tire. 

[EricJ]

1 hour ago, Will.iam said:

Retract the flaps before applying the brakes will significantly lower your chances of locking up the brakes and flat spotting a tire. 

I agree, and it's almost reflex for me to put the flaps up on rollout once the airplane is stable on the ground.   I fly C182s with an organization (CAP) and that's what our local ops guys teach, so there's compatibility there.   I was helping relocate some airplanes and flying left seat in another squadron's airplane with one of their guys, and he got very upset when I brought the flaps up on rollout at their airport, going on about how that's how people retract the gear on the runway so it's unsafe, etc., etc.   There are still those who think it's a bad idea.